Single-polysilicon electrically erasable programmable read only memory, herein, (single-poly EEPROM, or SP EEPROM) can be an effective, low cost mechanism for providing non-volatile memory in a variety of computer related applications, such as in small handheld digital devices like cellular telephones, personal digital assistants (PDA's), etc. SP EEPROM utilizes a simple fabrication process that can be programmed and erased multiple times without utilizing the expensive and very inconvenient UV erasure technologies.
Computers and other digital devices are sometimes used to digitally adjust or trim analog to digital converters (ADC), digital to analog converters (DAC), or to program precision voltage references, for example, by programming EEPROMs coupled to trimming resistors. In making these digital adjustments of such analog devices, however, many such EEPROM devices, trim resistors and a correspondingly large die area may be required to obtain an accurate trim level or voltage reference. Although double-poly (DP) EEPROMs may also be used for such analog adjustment in a smaller die area, the DP EEPROM technology often requires expensive additional processing operations.
Accordingly, it would be desirable to provide a relatively small memory device that can be electrically programmed to obtain an accurate adjustment level, while utilizing the simpler and lower cost fabrication technology of a single-poly EEPROM device.